The cornea, and in particular the anterior corneal surface shape, is the major contributor to the focusing properties of the eye. This, in addition to its accessibility, has made it an attractive site for manipulating refractive errors. In excess of 11 million Americans have amounts of myopia requiring optical correction; many have the desire to be able to function effectively without the need for that correction. There are several techniques in current use for the surgical correction of myopia; each has its advantages and limitations. Complications, of varying types, have been reported for each, including dissatisfaction with the resultant optical performance. The major objective of this project is to investigate ways of maximizing that optical performance. A first step is to validate procedures that will more accurately assess optical performance than are in present use; the techniques need to be ones which more reliably indicate optical performance when carrying out everyday tasks. These are to e used to extend analysis of the optical properties of the normal cornea beyond the usual case of centered symmetrical systems and axial imagery. The effects of corneal refractive surgery, of specific types and for particular refractive error groups, will then be assessed by the same procedures. The sources of diminished optical performance can then be recognized, and possible objectives to optimize such performance indicated. Many post- surgical patients have unsatisfactory residual corneal optics; clinical guidelines on the need for and efficacy of rehabilitation procedures (such as contact lens fitting) can be established with these assessment techniques. Such analyses can also be extended to more wide-ranging corneal abnormalities, allowing the formulation of a fuller understanding of the basis of optical degradation with corneal disturbance.